Crystal structure of Human ASB9-2 and substrate-recognition of CKB

Protein J. 2012 Apr;31(4):275-84. doi: 10.1007/s10930-012-9401-1.

Abstract

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9) is a specific substrate-recognition subunit of an elongin C-cullin-SOCS box E3 ubiquitin ligase complex. It recognizes its substrate, brain type creatine kinase (CKB), using the ankyrin repeat domain; and facilitates the polyubiquitination of CKB to mediate proteasomal degradation through the SOCS box domain. HASB9-2 is an isoform of hASB9 that contains one ankyrin repeat domain. In this study, the crystal structure of hASB9-2 is shown at 2.2-Å resolution using molecular replacement. Overall, hASB9-2 forms a slightly curved arch with a characteristic L-shaped cross-section. Amino acid substitution analysis based on docking experiments revealed that His103 and Phe107 in hASB9-2 are essential for binding to CKB. Analysis of truncation mutants demonstrated that the first six ankyrin repeats along with the N-terminal region of hASB9-2 contribute to the interaction with CKB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Ankyrin Repeat
  • Binding Sites
  • Creatine Kinase, BB Form / chemistry
  • Creatine Kinase, BB Form / genetics
  • Creatine Kinase, BB Form / metabolism*
  • Crystallography, X-Ray
  • Humans
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Sequence Alignment
  • Substrate Specificity
  • Suppressor of Cytokine Signaling Proteins / chemistry*
  • Suppressor of Cytokine Signaling Proteins / genetics
  • Suppressor of Cytokine Signaling Proteins / metabolism*

Substances

  • ASB9 protein, human
  • Suppressor of Cytokine Signaling Proteins
  • Creatine Kinase, BB Form

Associated data

  • PDB/3D9H